Stock material or miscellaneous articles – All metal or with adjacent metals – Having metal particles
Patent
1981-09-28
1984-06-19
Hunt, Brooks H.
Stock material or miscellaneous articles
All metal or with adjacent metals
Having metal particles
428554, 428567, 419 8, 419 27, 419 25, 419 47, B22F 300, B22F 326
Patent
active
044553536
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of producing an article which consists mainly on the one hand of sinterable material which, before it is sintered, can be given a relatively easily shaped state and has the characteristic of forming a relatively porous body during sintering, such as metal powder, and on the other hand of a matrix consisting of a metal with a lower melting point than the sintering temperature for the sinterable material. The method comprises filling a mould with powder or grains or the sinterable material, said mould having a mould surface which defines the shape of the article, heating the contents of the mould to the sintering temperature of the sinterable material so that a powder body is obtained, melting a matrix metal and causing it to filtrate into the powder body, and thereafter causing the matrix metal to solidity.
The invention also relates to an article produced in a mould which defines the contours of the article, which article consists mainly of a composite material comprising on the one hand a porous body of a metal powder which is more or less firmly sintered together, and on the other hand a matrix which is obtained by infiltration of an infiltrand consisting of an alloy with a lower melting point than the sintering temperature for said metal powder, which matrix fills pores of the porous body. In particular, the invention relates to a mould in a moulding tool such as a plastics moulding tool, a diecasting tool etc., with satisfactory strength and polishing capacity.
BACKGROUND OF THE INVENTION
Moulds of the above-mentioned kind and a method for producing them are already known, for example through the Swedish published Patent Application No. 76 00895-2 (GB No. 1 541 446). This known invention has also begun to be used in practice for the production of moulds in plastics moulding tools and, within this field, has represented a considerable technical advance in comparison with moulds produced in a conventional manner, primarily because the production costs are lower but also because they can be produced much more quickly which in many cases is of decisive importance.
It is also known to dispose cooling passages in moulding tools with the object of causing the products which are to be moulded in the tool to solidify more quickly and/or to bring about a controlled solidifying process. Conventionally, these cooling passages are produced by drilling in the tool or the material of the tool. For natural reasons there are great limitations to this conventional technique. For example, it is not possible to drill curved cooling passages; only straight passages or passages composed of straight portions. Only exceptionally can the passages be placed so that they "cover" all the moulding surfaces of the tool or even considerable parts of these, from the cooling point of view. Another disadvantage of cooling passages which are produced in conventional manner by drilling is that their walls do not have any better resistance to corrosion than the resistance of the material of the tool to corrosion. This applies both to moulding tools produced conventionally and to moulding tools of the kind given in the definition of the technical field of the invention. During use of the tool, the cooling water can therefore corrode the cooling passages so that these become wholly or partially blocked. Admittedly, this can be counteracted in certain cases by means of corrosion inhibitors or by lining the cooling passages with a more corrosion-resistant material. There are great limitations to both these possibilities, however, and in all circumstances they involve complications which are such serious complications when it is a question of lining, that this method is scarcely realistic in practice.
A specific complication in producing the composite article given in the technical field of the invention results from the tendency of the matrix metal to shrink in connection with the solidification. Normally, the solidification does not take place simultaneously in all parts of the po
REFERENCES:
patent: 2942970 (1960-06-01), Goetzel et al.
patent: 3262190 (1966-07-01), Rostoker et al.
patent: 3773506 (1973-11-01), Larker et al.
patent: 3915699 (1975-10-01), Umehara et al.
Hunt Brooks H.
Uddeholms Aktiebolag
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